Expansion bolt

ABSTRACT

An expansion bolt comprising a shank having threads at one end and at least one longitudinally extending external groove in the other end of the shank. The groove is provided with an inclined portion and a relatively deep portion with an expansion means disposed within the shank in said groove to yieldingly urge a wedge member, disposed in said groove, outwardly into wedging engagement with the wall of an opening.

United States Patent 1 Lerich [451 July 10,1973

[ EXPANSION BOLT [76] Inventor: Lester Lerich, 30 Morningside Drive,Lakewood, C010.

[22] Filed: May 6, 1970 [21] App]. No.: 47,927

Related US. Application Data [62] Division of Ser. No. 408,282, Nov. 2,1964,

abandoned.

[52] US. Cl. 85/79, 85/66 [51] Int. Cl. Fl6b 13/04 [58] Field of Search85/79, 66, 63, 8.3; 285/105 [56] References Cited UNITED STATES PATENTS2,287,395 6/1942 Reynolds 85/66 2,774,273 12/1956 Olson 85/79 2,949,6878/1960 Peklay et al. 85/8.3

3,216,306 11/1965 Taylor 85/79 3,304,828 2/1967 Karhu 85/66 FOREIGNPATENTS OR APPLICATIONS 860,124 2/1961 Great Britain 85/8.3 1,056,36310/1953 France 85/79 1,305,740 8/1962 France 85/79 PrimaryExaminer-Marion Parsons, Jr. Attorney-John E. Reilly 5 7] ABSTRACT Anexpansion bolt comprising a shank having threads at one end and at leastone longitudinally extending external groove in the other end of theshank. The groove is provided with an inclined portion and a relativelydeep portion with an expansion means disposed within the shank in saidgroove to yieldingly urge a wedge member, disposed in said groove,outwardly into wedgv ing engagement with the wall of an opening.

10 Claims, 6 Drawing Figures EXPANSION BOLT This is a division ofapplication Ser. No. 408,282, filed Nov. 2, 1964 now abandoned.

This invention relates to novel and improved fasteners, and moreparticularly relates to an expansion bolt characterized by havingimproved anchoring means which upon insertion into a bolt holeautomatically will anchor the bolt against outward displacement from thehole in a reliable manner.

In the construction and design of anchor or expansion type bolts, it ishighly desirable that the bolt assembly be made of a minimum number ofparts arranged such that the bolt diameter will closely approximate, orbe equal to, the size of the bolt hole; and upon insertion into the holeautomatically will become set or anchored in place without necessity ofmanipulating the anchoring elements from either end of the bolt holethus making it advantageously suited for use in blind holes. Further,that the bolt anchoring assembly including the actuating means thereforbe wholly contained within the inserted portion of the bolt so as not tobe exposed or otherwise subject to misalignment or accidentaldisplacement upon insertion into the opening, while at the same timewill not in any way interfere with insertion of the bolt through theopening. Accordingly it is a foremost object of the present invention toprovide for a novel and improved expansion bolt which is so constructedand arranged that the actuating means for expanding the anchoringelements into anchored relation within a bolt hole provided in a wallstructure or the like are located and contained within the insertedportion of the bolt assembly.

It is another object of the present invention to provide for an anchorbolt assembly which is so designed as to permit the bolt size toapproximate the hole size and with the anchoring elements being sodisposed thereon as not to interfere with insertion of the bolt into thehole; and furthermore wherein the anchoring elements are rapidlydisplaceable into wedging engagement under a minimum of outwarddisplacement of the bolt from the hole.

It is a further object of the present invention to provide for a boltassembly of the anchor or expansion type which is of simple andinexpensive construction and wherein each given bolt size is conformablefor disposition in different sized openings within limits; andspecifically, wherein the anchoring means are displaceable outwardlyfrom a position in flush relation, or substantially so, to the outerperipheral surface of the inserted portion of the bolt to a positionprotruding laterally and outwardly into firm wedging engagement againstthe wall of the opening.

It is a still further object of the present invention to provide in ananchor bolt for a novcl and improved actuating means in the form of anexpansible insert wholly contained within the inserted portion of thebolt automatically to control outward circumferential expansion of oneor more anchoring elements into wedging engagement within a bolt holeupon tightening or outward displacement of the bolt from the hole.

The above and other objects, advantages and features of the presentinvention will become more readily appreciated and understood from aconsideration of the following detailed description of alternate formsof invention when taken together with the accompanying drawings inwhich:

FIG. 1 is a view, partially in section, of one form of expansion bolt inaccordance with the present invention and illustrating in dotted formoutward displacement of the anchoring elements into wedging engagementwith the wall of an opening.

FIG. 2 is a section view taken on line 2-2 of FIG. 1.

FIG. 3 is a view, partially in section, of an alternate form ofexpansion bolt, in accordance with the present invention.

FIG. 4 is a sectional view taken on line 4-4 of FIG. 3.

FIG. 5 is a view of another alternate form of expansion bolt, similar toFIG. 3, incorporating a modified form of anchoring element andexpansible insert.

FIG. 6 is a sectional view taken on line 6-6 of FIG. 5.

Referring in detail to the drawings, an anchor bolt assembly isillustrated in FIGS. 1 and 2 which is broadly comprised of a bolt member10 having a threaded portion 11 and shank portion 12, the latter beinginsertable into an opening or bolt hole 13 which for the purpose ofillustration may be formed in the wall 14 of a building structure or thelike. As shown the shank 12 is generally circular in cross-sectionhaving a smooth outer peripheral surface in which is formed one or moreexternal grooves 16 each for reception of an anchoring element 17. Ashere represented, a pair of grooves 16 are formed in diametricallyopposed relation to one another adjacent to forward end 19 of the shankwith a common guide opening or slot 20 extending between the grooves andintersecting a transverse slot 22 extending intermediately between thegrooves 16 for reception of an expansible member in the form of acompressible insert 23.

In configuration, each groove is of generally concave shape being curvedinwardly to form spaced parallel sidewalls 24 and an inner areuatebearing surface 25 inclining or curving outwardly in opposite directionsfrom an intermediate, relatively deep recessed area of the groove intorelatively shallow recessed areas and terminating at the peripheralsurface portion of the shank. In turn, the common slot 20 between thegrooves in cross-section is preferably of elongated rectangularconfiguration being of reduced width in relation to the width of thegroove to provide spaced sidewalls 26 and opposite end surfaces 27 and28 which in a manner to be described limit the movement of the anchoringelements in relation to the groove. The transverse slot 22 also is ofrectangular configuration, but is enlarged in relation to the size ofthe common slot 20, and is formed for disposition of the insert 23 indirect communication with the common slot.

The anchoring elements 17 are preferably in the form of areuate wedgescorresponding in size and shape to the grooves 16. Accordingly eachwedge includes parallel sides 30, an outer flat surface 31, and an innercurved or areuate cam surface 32 complementary to the bearing surface 25and which intersects the outer surface 31 at opposite ends to formrelatively sharp edges 33. v

In order to control movement of each wedge 17 from a position lyingsubstantially within the groove, as illustrated in full in FIG. 1, to anoutwardly displaced position, as illustrated in dotted'form, a guidemember in the form of a generally rectangular pin 35 is directedinwardly from each inner cam surface 32 in offset relation to the centeraxis of the wedge for insertion into one end of the common slot 20. Inthis relation, each pin 35 normally is disposed along the end surface 27of the common slot away from the forward end 19 and is ofa length to beyieldingly engaged by the insert 23 and urged outwardly a sufficientdistance for the outer wedge surface 31 to make contact with the wall ofthe opening.

The compressible insert 23 is preferably in the form of a generallyrectangular block of resilient material, such as for example a rubber orrubberlike material, which is dimensioned to be slightly larger than theslot 22 so as to require forcing under compression into the slot.Accordingly, in assembled relation, the insert 23 will exert outwardpressure tending to force each of the pins 35 and wedge elements 17outwardly away from the surface of the shank; and upon insertion throughthe opening 13, any tendency of the wedges to become displaced intowedging engagement with the wall of the opening will be restricted bythe pins 35 abutting the end surface 29 of the common slot so that thewedges will be constrained to remain in a position with the outersurfaces 31 substantially parallel to the longitudinal axis of theshank. Once inserted in place, however, the limit pins 35 are slidableforwardly through the slot 20 toward the forward end 19 of the shank topermit outward sliding movement of the wedges 17 along the groovebearing surfaces 25 to force the forward edges 33 into wedgingengagement with the surrounding wall surface of the opening. In the formshown, this action may be initiated by a suitable washer 38 and aninternally threaded nut 39 disposed on the threaded portion 11 of thebolt assembly and which upon tightening against the wall surface 14 willexert the necessary outward pressure on the bolt to cause outwarddisplacement of the wedges 17 into anchored relation with the wallsurface of the opening.

In assembly, and for the purpose of shipment, the wedges may betemporarily retained in assembled relation by a retainer band or ring,such as, a retainer ring of the type shown and described with referenceto FIGS. to 13 and which will easily expand or break when the wedges areexpanded. For instance, under tightening pressure of the nut 39 andwasher 38 against the wall surface 14, the retainer ring would be brokenunder the force of the wedges being displaced outwardly into wedgingengagement.

In the form shown in FIGS. 3 and 4, like parts are correspondinglyenumerated and again a bolt assembly may suitably consist of or includea bolt member 10 having a threaded portion 11 and shank portion 12. Inthis form, however, a single groove 40 is formed adjacent to the forwardend of the shank for reception of a wedge element 17 of the type shownin FIGS. 1 and 2, andthe groove having spaced parallel sidewalls 41 andan inner arcuate bearing surface 42. To permit wider latitude ofmovement of the single wedge 17 through the groove 40 than in the formshown in FIGS. 1 and 2, the off-center 'pin 35 rides in a forwardlycurved guide slot 43 extending along the bearing surface from the deeperrecessed portion of the groove to the forward relatively shallowportion. The curved guide slot is of reduced width in relation to thewidth of the groove and includes opposite end surfaces 44 and 45 tolimit movement of the pin 35 so as to permit the wedge to advance in aforward direction only from its disposition within the groove as shownto an expanded position having its intermediate, relatively thicksection disposed at the outer surface of the shank; or, in other words,will permit about one-half of the wedge to be laterally displaced fromthe groove angularly toward the wall of the opening.

A compressible insert 46 is positioned in a recess 47 directly behindthe deeper recessed area of the groove 40 with one end of the slotforming an inward continuation of the end surface 44 of the guide slot.Again the insert 46 is composed of a resilient material and is enlargedin relation to the size of the recess so as to be inserted undercompression within the recess prior to positioning of the wedge in placewithin the groove. Additionally, the outer peripheral surface of theshank opposite the groove may be knurled or otherwise roughened, asdesignated at 49, to cooperate with the wedge in establishing firmanchoring engagement with the wall of the opening.

In assembled relation, temporary retaining means may be placed over thewedge to hold it in place for insertion in the opening; and uponinsertion the wedge is disposed along the groove with its outer surfaceparallel to the longitudinal axis of the shank. However, when outwardpressure is exerted upon the shank tending to displace it from theopening, the limit pin 35 being free to slide forwardly through theguide slot, will permit the wedge to shift forwardly and outwardly alongthe arcuate bearing surface 42 into laterally displaced relation fromthe shank against the wall of the opening, as in the manner described inFIGS. 1 and 2; and further, will force the opposite knurled surface 50into wedging engagement with the opposite side of the opening.

In the form of invention shown in FIGS. 5 and 6 the shank portion 12 hasa groove 50 defining spaced parallel sides 52 and an arcuate cam surface53; and a relatively broad, elongated rectangular slot 54 extendsinwardly from an intermediate portion of the bearing surfacetransversely through a substantial thickness of the body for receptionof an expansible insert 55. The insert 55 is of oblong, generallyrectangular configuration and is enlarged somewhat in relation to thatof the slot 54 so as to require forcing into snug-fitting relationwithin the slot. Moreover, the insert is formed with an outwardly facingarcuate or concave guide slot 56 which traverses the deeper intermediateportion of the groove, and a forward curved guide slot 58 of limitedlength is formed along the inner bearing surface at the forward end ofthe groove as a forward curved continuation of the arcuate slot 56.

A wedge element 60 is positioned in the groove 50 having spaced parallelsides 62, a relatively flat outer surface 63 and an inner arcuate camsurface 64 complementary to the arcuate bearing surface of the groove;however, in place of a guide pin of the type shown in FIGS. 1 to 4, thewedge is provided with a somewhat elongated curved guide member 65 forinsertion in the arcuate guide slot 56. Accordingly, the wedge 60 may bealigned in the groove with one end of the guide member 65 abutting theend surface 54 of the slot 54; whereas the guide member is movable in aforward direction through the guide slots 56 and 58 to effect lateraldisplacement of the wedge.

The insert 55 is preferably composed of a resilient material to exertsufficient outward pressure against the inner surface of the wedge toforce it into contact with the wall of the opening, and again theimportant requirement is that the wedge be maintained in aligned orcentered relation along the groove so as not to interfere with insertionof the shank through the opening; then upon tightening or withdrawingthe shank the wedge 60 will be free to slide forwardly through thegroove for lateral displacement into firm wedging engagement with thewall of the opening or bolt hole.

From the foregoing, it will be seen from the various form of inventiondescribed that the anchoring elements will automatically displacethemselves outwardly into firm wedging or anchoring relation with thewall of the opening when outward tension is exerted upon the boltmember. Thus, the actuating or expansion means for the anchoringelements primarily serve to predispose the anchoring elements in suchrelation to the shank as not to interfere with insertion of the boltmember through the opening so that upon outward displacement ortightening the anchoring elements will move immediately into anchoringrelation with the wall. Moreover, since the entire assembly employed foranchoring is contained within the shank portion of the bolt, there is noneed for special actuating members projecting along the shank throughthe threaded or exterior part of the bolt, thus affording greaterlatitude in choice of opening size and length for each given size ofbolt. It is therefore to be understood from the foregoing description ofvarious alternate forms of the present invention, that various changesand modifications may be made in the specific design, construction andarrangement of parts. For example, the thickness of the wedges inrelation to the depth of the grooves in each form will be governedprimarily by the extent of lateral displacement required of the wedgesto establish contact and wedging engagement with the wall of theopening. Moreover, where two wedges are employed in combination as inthe form shown in FIGS. 1 and 2 the degree of displacement of each wedgefor a given size of opening would be much less than where a single wedgeis utilized, as in the form shown in FIGS. to 13, and accordingly thewedge size and distance of movement would be correspondingly less. Inthis relation, it will be further evident in FIGS. 10 to 13 that two ormore wedges disposed in circumferentially spaced grooves may be providedin place of the single wedge and groove arrangements shown therein.Thus, any such changes and others may beresorted to without departingfrom the scope and spirit of the present invention as defined by theappended claims and any reasonable equivalents.

What is claimed is:

1. In an expansion bolt, a shank including at least one longitudinallyextending external groove formed with an inner bearing surface incliningoutwardly toward the forward end of said shank from a relatively deepportion to a relatively shallow portion of the groove, wedge memberdisposed in the groove including an outer wedging portion movable intowedging engagement with the wall of the opening provided for said bolt,said wedge member having a radially inwardly projecting guide membermovable through a longitudinal guide slot communicating with the groove,said guide member and slot being so disposed in relation to said wedgemember and groove respectively as to limit movement of said wedge in aforward direction only from its disposition in the relatively deepportion of the groove into wedging engagement with the wall of theopening, and an expansion member disposed in said shank and yieldinglyengaging said guide member in a direction to yieldingly urge the outerwedging portion of said wedging member outwardly into contact with thewall of the opening so that upon withdrawal of said shank from theopening said wedge is automatically displaced outwardly into wedgingengagement with the wall of the opening.

2. In an expansion bolt according to claim 1, the inner bearing surfacefor the groove being of arcuate configuration, and said wedge memberhaving an inner cam surface complementary to the inner bearing surface.

3. In an expansion bolt according to claim 1, said expansion memberdisposed in a recess along the inner bearing surface of the groove toyieldingly engage said guide member.

4. In an expansion bolt according to claim 1, said guide member definedby a pin disposed in offset relation to said wedge member, said guideslot being disposed along the relatively deep portion of the groove.

5. In an expansion bolt according to claim 1, said expansion memberhaving an outer surface portion defining the longitudinal guide slot andinner bearing surface along a portion of the groove, and said guidemember being complementary to the shape of the outer surface of saidexpansion member.

6. In an expansion bolt, a shank including at least one longitudinallyextending external groove formed with spaced side walls and an innerconcave bearing surface curving outwardly in opposite directions from arelatively deep intermediate portion into relatively shallow portions atopposite ends of the groove, a wedge member substantially conforming insize and shape to that of the groove including an outer flat surfaceportion and an inner cam surface portion contacting the inner bearingsurface in the groove, a guide member on said wedge member movablethrough a longitudinal guide slot in the groove for movement of saidwedge member in a forward direction only through the groove, and anexpansion member composed of a resilient material and being disposedinwardly of the groove to yieldingly engage said guide member in urgingsaid wedge mem ber outwardly into contact with the wall of the openingso that upon movement of said shank in a direction to withdraw it fromthe opening said wedge member is movable forwardly and outwardly intowedging engagement with the wall of the opening.

7. In an expansion'bolt according to claim 6, the guide slot for saidguide member extending forwardly and outwardly along the inner bearingsurface of the groove, and said guide member projecting inwardly fromthe inner cam surface for movement in a forward direction through theguide slot with the cam surface sliding forwardly along the innerbearing surface for movement of said wedge member into wedgingengagement.

8. In an expansion bolt according to claim 6, the groove being formedadjacent to the forward end of said shank, and said shank further havinga roughened outer surface portion cooperating with said wedge to anchorsaid shank against withdrawal from the opening.

9. An expansion bolt comprising a shank provided with a pair oflongitudinally extending external grooves disposed in diametricallyopposed relation to one another, each groove including an inner bearingsurface inclining outwardly toward the forward end of said shank from arelatively deep portion in the groove, a wedge member disposed in eachof the grooves and wardly into contacting relation with the wall of theopening for continued movement into wedging engagement with the wall ofthe opening thereby to anchor said bolt against withdrawal from theopening.

10. An expansion bolt according to claim 9, wherein said expansionmember is defined by a block of rubber' like material inserted undercompression in the recess between the grooves.

1. In an expansion bolt, a shank including at least one longitudinallyextending external groove formed with an inner bearing surface incliningoutwardly toward the forward end of said shank from a relatively deepportion to a relatively shallow portion of the groove, wedge memberdisposed in the groove including an outer wedging portion movable intowedging engagement with the wall of the opening provided for said bolt,said wedge member having a radially inwardly projecting guide membermovable through a longitudinal guide slot communicating with the groove,said guide member and slot being so disposed in relation to said wedgemember and groove respectively as to limit movement of said wedge in aforward direction only from its disposition in the relatively deepportion of the groove into wedging engagement with the wall of theopening, and an expansion member disposed in said shank and yieldinglyengaging said guide member in a direction to yieldingly urge the outerwedging portion of said wedging member outwardly into contact with thewall of the opening so that upon withdrawal of said shank from theopening said wedge is automatically displaced outwardly into wedgingengagement with the wall of the opening.
 2. In an expansion boltaccording to claim 1, the inner bearing surface for the groove being ofarcuate configuration, and said wedge member having an inner cam surfacecomplementary to the inner bearing surface.
 3. In an expansion boltaccording to claim 1, said expansion member disposed in a recess alongthe inner bearing surface of the groove to yieldingly engage said guidemember.
 4. In an expansion bolt according to claim 1, said guide memberdefined by a pin disposed in offset relation to said wedge member, saidguide slot being disposed along the relatively deep portion of thegroove.
 5. In an expansion bolt according to claim 1, said expansionmember having an outer surface portion defining the longitudinal guideslot and inner bearing surface along a portion of the groove, and saidguide member being complementary to the shape of the outer surface ofsaid expansion member.
 6. In an expansion bolt, a shank including atleast one longitudinally extending external groove formed with spacedside walls and an inner concave bearing surface curving outwardly inopposite directions from a relatively deep intermediate portion intorelatively shallow portions at opposite ends of the groove, a wedgemember substantially conforming in size and shape to that of the grooveincluding an outer flat surface portion and an inner cam surface portioncontacting the inner bearing surface in the groove, a guide member onsaid wedge member movable through a longitudinal guide slot in thegroove for movement of said weDge member in a forward direction onlythrough the groove, and an expansion member composed of a resilientmaterial and being disposed inwardly of the groove to yieldingly engagesaid guide member in urging said wedge member outwardly into contactwith the wall of the opening so that upon movement of said shank in adirection to withdraw it from the opening said wedge member is movableforwardly and outwardly into wedging engagement with the wall of theopening.
 7. In an expansion bolt according to claim 6, the guide slotfor said guide member extending forwardly and outwardly along the innerbearing surface of the groove, and said guide member projecting inwardlyfrom the inner cam surface for movement in a forward direction throughthe guide slot with the cam surface sliding forwardly along the innerbearing surface for movement of said wedge member into wedgingengagement.
 8. In an expansion bolt according to claim 6, the groovebeing formed adjacent to the forward end of said shank, and said shankfurther having a roughened outer surface portion cooperating with saidwedge to anchor said shank against withdrawal from the opening.
 9. Anexpansion bolt comprising a shank provided with a pair of longitudinallyextending external grooves disposed in diametrically opposed relation toone another, each groove including an inner bearing surface incliningoutwardly toward the forward end of said shank from a relatively deepportion in the groove, a wedge member disposed in each of the groovesand each wedge including an inner cam surface movable in a forwarddirection only along the inner bearing surface of the groove for outwarddisplacement of each wedge into wedging engagement with the wall of theopening provided for said bolt, a common expansion member disposed in arecess between the inner bearing surfaces of the grooves, a guide memberextending radially and inwardly from each of said wedge members so as tobe yieldingly engaged by said expansion member and to yieldingly urgesaid wedge members outwardly into contacting relation with the wall ofthe opening for continued movement into wedging engagement with the wallof the opening thereby to anchor said bolt against withdrawal from theopening.
 10. An expansion bolt according to claim 9, wherein saidexpansion member is defined by a block of rubberlike material insertedunder compression in the recess between the grooves.